Method of generating and cutting gears



Dec. 29, 1953 Filed May 26, 1947 FIG.

K. B. TRACE 2,664,031

METHOD OF GENERATING AND CUTTING GEARS 5 Sheets-Sheet l JNVENTOR. Z5777 E. 7E/9CE Dec. 29, 1953 K. B. TRACE METHOD OF GENERATING AND CUTTING GEARS Filed May 26. 1947 5 Sheets-Sheet 2 55 4 56 @5 59 59A 66 a5 w a INVENTOR.

Dec. 29, 1953 K. B. TRACE 2,664,031

METHOD OF GENERATING AND CUTTING GEARS Filed May 26, 1947 5 Sheets-Sheet 3 INVENTOR. XE/Wvf 5. 276445 1953 K. B. TRACE 2,664,031

METHOD OF GENERATING AND CUTTING GEARS Filed May 26, 1947' 5 Sheets-Sheet 4 F/a/5. m F/G/6T F/GT/Z INVENTOR. fiTh fi. 76465-7 Dec. 29, 1953 K. B. TRACE 2,564,031

METHOD OF GENERATING AND CUTTING GEARS Filed May 26, 1947 5 Sheets-Sheet 5 321 L E 37 5-4 5 4 3? w 9;} H633 33 7 A //e //9 --1 FIG 34. a 3

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I /Z0/ ///9 I INVENTOR.

465/ THE 72/955 Patented Dec. 29, 1953 METHOD oF GENERATING AND CUTTING GEA Keith B. Trace, Detroit, Mich. "Application May 26, 1947, Serial No. 750,443

4 Claims.

My invention relates to a new and useful improvement in a gear cutting method.

It is an object of the present invention to provide a gear cutting method whereby a cutting element is constantly rotated and the Work-piece on which the gear teeth are to be cut is constantly rotated while the cutting element is in contact therewith. While there is a relative rotation of these parts, the cutting element will move aixally of the work-piecethe desired length but there is no relative radial movement between the work-piece and thecutting element and it is an object to provide a method whereby these factors may be present while the gear cutting is being performed.

Another object of the invention is the provision of a method of cutting gears whereby a plurality of cutting elements will successively operate upon the work-piece, the first operation being the cutting of a cavity of the proper depth, and the second operation the cutting of the cavity of the proper width. A third operation consists in forming and finishing the involute on one side of the cavity, and the fourth operation consists in forming and finishing the involute on the opposite side of the cavity. ihese operations may be performed by the use or four cutting elements having cutting teeth adapted to perform the four operations referred to, but it is an object of the present invention to also provide an arrangement whereby a single rotatable cutting element may have cutting teeth thereon divided into segments, one of the segments being provided with cutting teeth to perform operation Number 1, another segment with cutting teeth to perform operation Number 2, another segment with cutting teeth to perform operation Number 3, and another segment with cutting teeth to perform operation Number 4. t

It is an object to provide a method of cutting gears with a constant rotation of the work-piece and the 'eutter'whereby a very small stock may be used from. which to cut the gears and thisis particularly effective when a cutter divided into segments, as mentioned, is used.

Another object of the invention is the provision of a method whereby the teeth on the gear may be formed and whereby the cutters, which co-operate to cut the teeth, may be adjusted, thus compensating for any slight variations in the dimensions of the'cutting elements.

Other objects will appear hereinafter.

It is recognized that various modifications and changes may. be made in the details herein set forth and it "is intended that such shall be em- 2 braced Within the scope of the claims which form a part hereof. Forming a part of this specification ings in which,

Fig, 1 is a central, vertical, sectional view of a machine used for carrying out the method showing parts broken away and parts in side elevation,

Fig. 2 is a front elevational view of the machine used,

. Fig. 3 is a top plan view in fragment,

Fig. 4 is an enlarged fragmentary, elevational view showing the arrangment of the cutting element,

Fig. 5 is an enlarged sectional view taken on iine 5-5 of Fig. 3,

Fig. 6 is a fragmentary, sectional view taken on line 5-6 of Fig. 1,

Fig, 7 is a fragmentary, slightly enlarged sectional view taken on line l--'| of Fig. 1,

Fig. 8 is a fragmentary, elevational view showing the first step in the cutting operation,

Fig. 9 is a fragmentary, elevational view showing the second step in the cutting operation,

Fig. 10 is a fragmentary, elevational view showing the third step in the cutting operation,

Fig. 11 is a fragmentary view showing the are draw- .fourth step in the cutting operation,

Fig. 12 is an end elevational view of a work piece showing a cavity formed by the first operation,

Fig. 13 isan end elevational view of a workpiece showing the cavity after the second operation, Fig. 14 is a fragmentary, sectional view slightly enlarged taken on line l4l4 of Fig. 13,

Fig. 15 is a plan View of a cutter having the cutting teeth arranged in four segments,

Fig. 6 is aside elevational View of the cutter shown in Fig. 15,- Fig. 1'7 is a slightly enlarged peripheral, fragmentary view of a segment of the cutter shown inFig. 15, r

Fig. 18 is a slightly enlarged fragmentary, side elevational view of a segment shown in Fig, 15,

Fig. 19 is a fragmentary view taken on line 19-19 of'Fig. 18,

Fig; 20 is a fragmentary, side elevational view of that-portion of the cutter shown inFig.15 which embodies the cutting element No. 2, illustrated in fragment, I

Fig. 21 is a fragmentary plan view of that portion of the cutting element shown in Fig. 15 which embodies the cutting element No. 2,

Fig. 22 is an enlargedfragmentary, side elecutter which .13: t tional view of that portion of th element irlo. i,

Fig. 28 1s a view taken on line 2828 of Fig.

Fig. 29 is an enlarged, side elevational, fragenlarn-n disc embodying mentary view of a cutter showing a slight modification,

Fig. 30 is a fragmentary view taken on line 303-'J of Fig.

Fig. 31 is a fragmentary view taken on line Iii-3i of Fig. 29,

Fig. 32 is a fragmentary, side elevational view of a cutter showing a further modification,

Fig. 33 is a fragmentary, sectional view taken on line 33-33 of Fig. 32,

Fig. 34 is a fragmentary view taken on line 34-34 of Fig. 32.

Fig. 35 is a fragmentary, side elevational view of a cutter showing a further modification,

Fig. 36 is a view taken on line 35-46 of Fig. 35.

Fig. 37 is a view taken on line 3l3'i of Fig. 35.

In the drawings I have illustrated as an example a machine which is capable of performing the operation so that the gears are cut according to the method referred to herein. In this machine I have illustrated a body 2! having the bearing 28 projecting inwardly from one portion thereof and provided with the overlying supporting portion 25. Projecting upwardly from this portion 23 is a standard 30 which serves as the support for the lectric motor 3| which serves to drive the pinion 32. This pinion is in mesh with the idler 33 which in turn meshes with the gear 34 fixedly mounted upon the shaft 35. Fixedly mounted on this shaft 35 is a plurality of gears 35, 3'! and 38 so that the speed of rotation of the driven parts may be controlled. The transmission in itself forms no part of the present invention and is not illustrated in detail. Meshing with the gear 35 is an idler 33 with which meshes an idler 43 which in turn meshes with the gear 4! slidably mounted on the shaft 42 and adapted for rotating in unison therewith. The yoke projects outwardly from the slidable support 54 which is slidably mounted on the standards or guide rails 45 which project upwardly from the body 2?. Secured to this body 44 is a nut 46 in which is threaded a screw fill which projects through and is adapted to rotate rela tively to the lug d3 projecting outwardly from the body The screw 4'! is provided with a hand whee 53 whereby it may be rotated and as illustrated in Fig. 1, this screw Al is fixed axially relatively to the lug 4S. Slidably mounted on the shaft 42 and rotating in unison therewith is the gear the yoke 43 carrying the gear 50 longitudinally of the shaft 42 when the screw 41 is retated to move the supporting head 44. This gear meshes with the idler gear 5i which in turn meshes with the gear 52 fixedly mounted on the shaft 53. This shaft 53 carries a suitable column 54 on which the work-piece is positioned so that when the shaft 53 is rotated the work-piece retained by the column is also rotated.

The gear 32 meshes with the gear 55. Meshing with the gear 55 is the idler gear 56 which also meshes with the gear 51 the gear 55 being mounted on the shaft 53A and the gear 5'! being mounted on the shaft 51A shown in Fig. 6. The gear 55 also meshes with the gear 53 mounted on the shaft 58A and this gear 58 meshes with the cutter gear 59 mounted on the shaft 53A. The gear 55 meshes with the gear 60 mounted on the shaft 55A and this gear in turn meshes with the gear 61 fixedly mounted on the shaft 61A. The gear 55 meshes with the gear 62 mounted on the shaft 52A and the gear 62 meshes with the gear 63 which is fixedly mounted on the shaft 33A. Supported by the portion 29 is the head 55 on which is mounted the plurality of slides, one of these slides being provided for each of the shafts MA, 53A, 51A and 53A. They are similarly constructed and operate similarly so that a description of one will sufiice as a description for all. Slidably mounted on the slide is a carriage 53 in which the shaft 53A is journaled, and connected to the carriage 65 is a screw 57 so that upon a rotating of the screw 61, the carriage 66 may be moved inwardly and outwardly on the slide 55. This is to provide means for adjusting the apparatus to cut gears of different sizes. Each of the shafts 55A, 58A, 55A and 52A projects through one of the radiating arms 58 which may be keyed to the shaft 69 at various positions of rotation so that when the shafts 53A, 51A, etc., are moved outwardly, the gears 55, 58, 63 and 62 will be swung on the shaft 59 as an axis so that they remain in mesh with the gears 63, 5|, 59 or 5i as the case may be. I'hus, it becomes possible to space the shafts 57A, 59A, MA and 63A farther apart and yet maintain the necessary meshing of the gears for driving these shafts. Mounted on the lower end and rotated by each of the shafts 57A, 59A, BIA and 63A is a cutter, cutter A, cutter B, cutter C, and cutter D being designated in the order of their operation so that cutter A may be said to be cutter No. 1, cutter B cutter No. cutter C cutter No. 3, and cutter D cutter No. 4. In Figs. 8, 9, 10 and 11, I have designated the workpiece or blank from which the gear is to be cut by the numeral W. The teeth of the various cutters are differently formed to perform their different operations and a description of the cutting operation will now proceed.

The teeth on the cutter A are cut away as at H on the advancing edge or face. The outer edge of this cut away portion effects the cutting.

- While the teeth are located diametrically opposite each other, the cutting face or the face 74 on which the cutting edge is present does not extend diametrically but is inclined at an angle as clearly appears in Fig. 8. When the workpiece is positioned on the retainer 54, the support 44 may be moved upwardly so as to move the work-piece into engagement with the cutters positioned above as the face of the work-piece is engaged by the cutters the operation is as shown in Fig. 8, Fig. 9, Fig. 10, and Fig. 11. As the teeth of th cutter A enter the work-piece a recess 76 is formed in the advancing face of the work-piece the formation of these recesses being clearly shown in Fig. 8 and Fig. 1 It will be noted that the cutting is a continuous one and that the advancing edge is cutting the material directly ahead of it. Cutter A is, of course, rotating in the direction indicated by the arrow and the work-piece W is rotating continuously in the direction indicated by the arrow on it. Cutter No. 1 is positioned slightly. orapproximately five B and cutter B is slightly or approximately five thousandths of an inch axially ahead of cutter C. Cutter A is used to cut the depth and cutter B is used to cut to the proper width.

The teeth on cutter B are cut away as at E5 to provide an advancing face and theedge of this advancin face is the portion which does the cutting. As the tooth of cutter B enters the recess formed by cutter A, the tooth of cutter B will cut to widen the recess 78 so as tocut to the proper width.

The teeth of cutter C have a cutting edge which is tlie outeredgeof the face 71.; These teeth, in entering the cavity, do .thecutting onza pushing operation to form the involute" and to finish-the involute. As shown in Fig. 1G,'when the tooth enters'the cavity or recess It, the edge of the facing ll effects a cutting operation at its 'juncture with the outer face 82 and this cutting operation continues'on one face of the cavity so that the invoiute on one side of the recess or cavityis formed and finished. Consequently, the cutting operation of the teeth of cutter C is the cutting operation effected in a pushing manner as the cutting tooth is moving into the recess or cavity. In cutter D, the cutting tooth. does not efiect any cutting operation whil moving into the cavity but begins its cutting operation as it travels on its outward movement. The tooth 3B is cut away, as at 85, to provide a cutting edge on the end of the hook thus formed which serves to engage and cut away the opposite side of the cavity or recess to form and finish the involute at the opposite side so that there is no pro-forming of the involute and then anotherstep for finishing the involute.

It will be noted that all of the cutters are con stantly rotating and that the work-piece is constantly rotating and also that the cutters are con. stantly in contact with the work-piece. There is no movement radially inwardly and outwardly from the work-piece in order to effect the cutting. Moreover, it will be noted that the'cutters are moved axially and travel merely the length of the teeth.

This makes it possible to cut a gear which is concentric with its bore inasmuch as the workpiece rotates on its own axis as it is being out. It will be noted also that there is noindexing and that there is a constant feed of the work.- piece into the cutting members. Experience has shown that this method of cutting a gear is one which renders the gear truer to size and concentric, while at the same time, the gear cutting may be easily and quickly effected reducing the labor cost considerably.

It is believed obvious that while I have illus trated a mechanism for cutting the gears in which the four-cutters are mounted ona singlemachine that the method of using thesuccessive cutters for cutting successive parts of the tooth need not require a machine such as illustrated and that the method may be followed and carried out with other types of construction.

Experience has shown that under certain circumstances, in cutting gears with the method herein set forth, it is impracticable to use four sets of cutters as illustrated, for example, in Fig. 3. Particularly is this the case where the gear to be cut is a very small gear. Where the gear to be out is a small gear, it may be desirable to dispense with two of the cutters illustrated in Fig. 3 and perform the operation with a pair of cutters" This' may be carried further and-the operation may be carried on with a single cutter. In Fig 15, I have illustrated a cutting wheel lull divided into four segments, each segment being indicated into four segments, segment Si, segment S2, segment S3, and segment St. Each of these segments is provided with teeth which appear on cutterA of Fig. 8 and which are adapted toperform the first operation, namely, the cutting ofthe depth of the cavity. The teeth on segment S2 are the teeth which are illustrated on cutter B shown in Fig. 9 which are adapted to perform the second operation, namely, the forming. of thecavity to the proper width. The teeth .on segment S3 are the teeth shown on cutter C in Fig. 1G and the teeth on are the teethlshownon cutter D in Fig. 11. It is obvi= ousthat when the cutter is brought into engagement with the. work-piece and rotated in the direction indicated by the arro v on Fig. 15 that the various segments will successively be brought into engagement with the work-piece, each segment traveling around the periphery of workpiece before the successive segment engages. In using a cutter such as shown in Fig. 15, the relative rotation of the cutter and the work-piece will, of course, have to bear a certain proportion. Where four segments are used, such shown in Fig. 15, the work-piece would have to rotate at least four times as fast as the cutter for most efficient operation. It is believed obvious that any number of the cutter, shown in Fig, 15, might be used in a gear-forming operation and, if desired, all four of the cutters which are shown in Fig. 4 might be constructed as is the cutter shown in Fig. 15.. However, I prefer, when using the four cutters, to form each cutter with one kind of cutting tooth so that the cutter itself will per form a single operation. When using the cutter shown in Fig. 15, the teeth on segment i will perform the first operation, the teeth on se ment 2 the second, and the teeth on the segments 3 and 4 will perform the third and fourth operations. It is believed obvious that the location of the teeth on segments 3 and 4 may be alternated as the operation performed by the teeth on segment 4 might precede the operation of the teeth on segment 3.

It is believed obvious from a description of Fig. 15 that the cutter may be provided with any desired arrangement of the cutting elements or teeth. For instance, a gear could be successfully cut using a pair of cutters, one of the cutters having the cutting elements 1 and 2, and the other cutter having the cutting elements 3 and i. In this instance, the cutters would be used in pairs or multiple pairs. Again, a cutter might be used having the cutting elements 1 and evaporating with a cutter having the cutting elements 3 and a used in pairs or multiple pairs. The operation might also be performed with the cutter having the-cutting elements 1 and S andthe cutting elements 2 and4 used inpairs or multiple pairs.

In Fig. 29,- I have illustrated the cutter its havingthe cutting edges :69 and he formed on the teeth. This cutting edge ltd is the cutting edge found on cutter No. 3 and cutting edge I it is the cutting edge found on cutter No. i so that this cutter I08 is combining on each tooth the cutting edges so that the tooth will perform operation N o. 3 and operation No.

In Fig. 32, I have indicated a cutter Ill having the cutting edges ilil, ii3, lit, and H5 formed thereon, the cutting edge 542 being No. 1 cutting edge and adapted for performing the first operation, the cutting edge i it being cutting edge No. 2 adapted for performing oeration No. 2, cutting edge H3 being the cutting edge No. 3 adapted to perform operation No. 3 and cutting edge H5 being the cutting edge No. i adapted to perform operation No. 4. Consequently, with a cutter of this type, each tooth embodies all four cutting elements that each tooth will perlorm the four operations. As y in Fig. 33, these cutting edges c .oy cutting back the face of the cutter as at H3, and H3. This cutting been pr rides clearance for such chips at ma o =ntercd or formed.

I have shown slight modification embodyni the cutter iii-E having the teeth I28 provided 't g E corresponding to the cu he cutter No. 3 which is illus The cutting edge 522 on ed. in f 23, is cut back "he tooh l i. In the form sitting back is eliminated c sack so that the periphery the provide the lie operations.

It is, c iscqucntly, that I have provided a method of cutting" gears whereby the four steps to depth, '"ening it to width and then for ring and finishing the involute on oppos he tooth or cavity may be accoinpli while the various coin for cutting \ror large sizes.

The direction of rotation of 11-8 cutter and the workpiece is indicated by t e arrows shown in Fig. 8, Fig. 9, 1e, and i1, and it will be noted that the cutter rotates in the opposite direction to the dir ction of the work-piece.

From the descriptio "ven, it is believed obvious that instead of for ring a cutter comprising segments, each s hav ng a number of spec ified cutting teeth such lust-rated in Fig. 15,

cutter could be made e cutting teeth formed thereon s" *c cally, each toot cutting; teeth L woulc follow each other in sequence on t" -ut er, or a cutter could be made having the th 1 and 2 following each other witl the combination tooth following having the cutting edges or cutters 3 and 4.

What I claim is:

1. The r; ethod or" cutting a gear consisting in rotating solid one med-upon blank from which th is he on its own axis, face of said blank into the of cutters may he provided -p1-\ es very small sizes or very on station of said ees of prop r depth in the a and then bringing nt with the teeth of 'i'on opposite to the k for cutting said ecchen bringing one f each oi recesses into contact with the teeth of a cutting element rotating in a direction opposite to the direction of rotation of said blank for establishing and finishing on one side the involute and then bringing the opposite side of said recess into engagement with a cutting tooth of another rotating cutter rotating in a direction opposite to the direction of rotation of said blank for cutting and finishing the involute on the opposite side of said recess.

2. A method of cutting a gear consisting in feeding a solid unw rked-upon blank from which a gear is to be formed so as to engage the marginal face thereof adjacent the mar incl edges with the teeth of acutter element rotating on its axis for forming cavities of proper depth in the marginal portion of the blank and then bringing said cavities into engagement with the teeth of a second cutter rotating on its axis for cutting said recesses to proper width and then bringing opposite sides of said cavity successively into engagement with separate cutting elements for forming on said sides the involute and finishing the same.

3. The method of cutting a gear consisting in rotating a solid unworked-upon work-piece on its axis in one direction and subjecting the peripheral margin of said work-piece to the action of cutters rotating in the opposite direction and provided with teeth for cutting a recess of a proper depth in the face of the work-piece and teeth for cutting said recess to a proper width and two sets of separate teeth for successively cutting opposite sides of said recess to the shape and finish of the involute of the tooth required.

4. The method of cutting from a solid cylindrical blank a cylindrical gear of the spur or hellcal type in which the tooth space runs generally longitudinally and out of one end of the cylinder comprisin rotating said blank, feeding the end of the rotating blank into a cutting element rotating in the opposite direction for cutting a cavity of the depth of a tooth space, and then contacting said end with a cutting element rotating in said opposite direction for cutting the cavity to the proper width of a tooth space, and then contacting said end with a cutting element rotating in said opposite direction for forming and finishing an involute on one side of said cavity, and then contacting said end with a cutting element rotating in said opposite direction for forming and finishing the involute on the opposite side of the cavity.

KEITH B. TRACE.

References Cited in the file of this patent UNITED STATES PATENTS 

